Preparation and purification of primary aromatic amine hydrohalides of the benzene series



Sept. 20, 1 932.

M. EL PUTNAM ET AL 1,878,512 PREPARATION AND PURIFICATION 0F PRIMARYAROMATIC AMINE HYDROHALIDES OF THE BENZENE SERIES Filed Sept. 14. 1929 iINVENTORS I BY ma/lk M ATTORNEY formation and purification of amine hyhalide, when the body vaporized is continually renewed by prepaingimpurities, such oxidation products remain behind as a residescribedand'pointed out Patented Sept. 20, 1932 NITED] STA ATE Q F C I MARK E.PUTMAM ANnLINnLEY E. ILLS, 0F MI LAND, MIGHIGARASSIGNQR 'ro THE nowCHEMICAL COMPANY, OF IDLAND, MICHIGAN,

. MICHIGAN A CORPORATION 015,

:enErARATIoN AND ruEIE CA'rIoN oE rEIMAEY AEoMAT AMINE HYnnoIIALInEs OFr E-BE zENE SERIES 7 a lication-med September M, 1929. Serial No.392,729.

' The present inventionrelatesto the prep'a-- ration of aminehydrohalides, particularly aromatic amine hydrohalides, and moreparticularly to methods for the preparation of aniline hydrochloride.

In a pending application by Lindley E."

Mills, one of the present inventors, Serial No. 392,727, filed September1i, 1929,a method for the purification of amine hydrohalides has'be'endisclosed, in which such compoundsv are vaporized-and condensed in thepresence of the corresponding hydrogen halidegas.

We have now found that such method may be modified and adapted for theconjoint'prep aration; and purification of an amine hydroof hydrohalidebeing ration of further quantities thereof in sltu by the addition offree amine to the hydrohalide being vaporized, the amine then react- Ving with the hydrogen halide gas .present to form the corresponding inturn is vaporized and removed from the reaction vessel. p

In such improved method for the conjoint halides the operative steps arereduced in number and less apparatus is required than c gen halide, e.

in methods hitherto employed. High boilas I diphenylamine, or

due in the vaporization zone, and a pure, white, dry product is obtainedwithout resorting to the use of solvents or diluents with thedisadvantages attendant upon the use there-- ofy-i .To theaccomplishment of the foregoing and related ends, oft-he method'andmeans} the invention, then, consists The single figure there appearingillustrates diagrammatically one form of appa- 1 connected to ahydrohalide, which product.

hereinafter fully in the claims, the' ,ratus suitabl for carrying outour new d pr ved process.

Referring tothe drawing, a 'reservoir is tubular reactor 2 by means" ofa pipe'7 which is proyidedwitha valve 8. f

Said reactor is provided with an exit pipe 5 which is fitted with avalve '6. Heating means 7 is iprovided for saidreactor, here shownas anexternally wound electric resistor"*wire, Thermometers 3 areinsertedinto the reactor space as shown. Reactor 2 connects at one endwith a cooling and condensing chambers, and at the opposite'end'thereofisprovidedwith a gas inlet purpose of withdrawing residual materialsfrom V the reactor. "Exit tube or pipe 9 leads from chamber i'to acircula-tory pump 1O 12; .Pipe 5 is forthe" Y which in turn is connectedby means of pipe 11' with gas inlet12, pipe-'11 being provided 'ustpreceding its junction with a valve'13 with gas inlet 12. A coveredopening l l'is provided in chambers for discharging" the Aniline, orother amine, is gradually intro duced from reservoir 1 by means of tubeinto reactor 2 which vaporize such amine and also the amine salt;resulting from the reaction; I Gaseous hydrog. hydrogen chloride,enters] reactor 2 through inlet 12 and reacts with the amine in liquidand/or vapor state to gform the corresponding amine hydrohalidejwhic'his carried 'by he gas'current into cooling; chamber 4 wherein thegreater part thereof is condensed. Residual gases, which may carry" asmall amount of product, passffrom-cool ing chamber cycled by meansoflcirculatin'g pump "10 and pipevll', such ga sesj'reentermg'thereactori through inlet pipe 12.1 Y I f The following detailed examplesare given 7 f 'i' by way of illustration of our improved method, but itis understood that such examples, are not to be interpreted upon theinvention;

Ewample 1 grams aniline is run slowlyinto reactor 5- 2,hcated to 200215?0., through which a as a limitation I isheated sufficiently t 4 throughtube 9 an d are re-*} 7 I procedure similar to that mentioned in .Ex'-yield being almost quantitative,

or more groupssuch as alkyl the productobtained in-a Example 2 C.through which acurrent of dryfgaseous hydrogen chloride is' constantlypassing, and

Example 1. The yield of white, crystalline ortho-toluidine hydrochloride(Map; 213

is practically quantitative. I

v Example I v Aniline hydrobromide is tained by a ample 1, the and theproduct melting at 285 C.

We do not limit ourinvention to the mate rials specifically mentioned inthe-examples. Other equivalent amines, e. g,' the 'alkyl aliphaticamines, or other aromatic amines such as anilines wherein either the"nitrogen.

or the ring or both may be substituted byone groups, may be utilized byrestricting the vaporization temperature below that sition orrearrangement ofthe amine hydrohalide product may "occur' The hydrogenhalidegas used, maybe diluted with :a gas unreactive with the reactioncomponents, i. e.

nitrogen, and the vaporized salt maybe carried to the -cooli-ng chamberby a current of,

The process may be oper-"- ated ei-therin batch or continuously,'and maysuch diluted gas;

be carried out under either reduced or increased ;pressure, ifdesi-red.

= on aniline about 220 line and hydrochloric acid place, and 'at about245.G. ajmixtureof aniline hydrochloride and a line resulting in adiscolored product or one which becomes so contact with air.I-Iowever,-if the -vaporization is carried out in such way thatthevapors are condensed in an atmosphere of hydroehloric acid, theproduct condensed consists of a pure aniline hydrochloride substantiallyuncontaminated by tree aniline. The upper temperature limit for "thevaporization- 0f aniline hydrochloride in an atmosphere of gaseoushydrogen chlo- 50 grams ofortho-toluidine is likewise T slowly into saidreactor 2, heated to 215'225 manner similar to avoided, and (6) the the.one explained, change point at which decompo hydrochloride heated to I(1, dissociation thereof into -ani-* begins to take small amountof Ifree aniline d istills. the" presence of theanion standing, especiallyin hydrochloric acid is approximately 250 0., above which decompositionthereof begins to occur with formation of rearrangement, condensati0n,or. decomposition products, such as diphenylamine, etc. For other aminohydrohalides the temperatures employed may vary somewhat from thepending upon the particular salt employed.

In summation, our invention involves reacting in absence of a solvent,between an amine and a hydrogen halide gas, i. e. hydrogen chloride orhydrogen bromide, vaporizmg the reaction product in presence of excessof the latter, separating said product from excess hydrogenchloride gasand returning the latter tothe initial reaction step Among theadvantages of the present new and improved method are, (l) a dry productisobtained directly from thereaction components, (2) such product is ofthe highest purity, further purification thereof being unnecessary, ;(3)essentially quantitative yields are *obtained, i(l) the use of solventsor dilucuts with attendant disadvantages is eliminated, (5) frequenthandling of materials is purified product may be producedat a lowercost.

:Qthermodes of applying theprinciple of our invention may be em. loyedinstead of being made as .regardsv-the method herein disclosed, providedthe step :or stcps stated by any of the following claims :or theequivalent of such stated step or steps beemployed; V

We therefore particularlypointqout .and distinctly claim as ourinvention 1'. Ina method of making .a primary aromatic amine hydrohalideof the benzene series, thesteps'which consist in reacting a primaryaromatic amine of the benzene series with .a gaseoushydrogen hahde inthe ab- I sence of a solvent, and

simultaneously vaporizrng the aromatic tion zone, and separatelycondensing said amine hydrohalide in the presence of an excess of thegaseous hydrogen halide.

maticl amine hydochloride of the benzene series',the steps which consistin reacting a primary aromatic amine ofthe benzene series with gaseous'hydrogen chloride' in the'absence'of a solvent,andsimultaneouslyvaporzing the; aromatic am ne hydrochloride formed, removing the vaporsfrom the react1on zone and separately condensing said aminehydrochloride in the presenceof excess gaseous hydrogen chloride. l v

method of makingan aniline hydrohailide, the steps which absence of asolvent vaporizing the aniline hydrohal-ide iormed, removingthe vaporsfrom the reaction zone, and separately condensing the aniline hydro- Iamine hydrohalide formed, removing the vapors from the reac- I 2, Inamethod or making a primary aroconsist -in reacting aniline with agaseous hyd-rogenha'lide in'the and simultaneously halide in thepresence of an excess of the gaseous hydrogen halide.

4. In a method of making aniline hydrochloride, the steps which consistin reacting aniline with gaseous hydrogen chloride in the absence of asolvent and simultaneously vaporizing the aniline hydrochloride formed,removing the vapors and separately condensing the aniline hydrochloridein the presence of excess gaseous hydrogen chloride.

5. In a method for the conjoint preparation and purification of aprimary aromatic amine hydrohalide of the benzene series, the stepswhich consist in vaporizingsuch amine hydrohalide in the presence of acurrent of the corresponding hydrogen halide gas and simultaneouslyincreasing the quantity of said aromatic amine hydrohalide by introthecorresponding primary aromatic ducing amine of the benzene serles to thevaporizing zone, whereby additional aromatic amine hydrohalide isformed. 7

6. In a method for the conjoint preparation and purification of anilinehydrochloride, the steps which consist in vaporizing said compound inthe presence of a current of gaseous hydrogen chloride andsimultaneously introducing anlline into the vaporizing zone, whereby anadditional quantity of vaporized aniline hydrochloride is formed andremoved from the reaction zone, separately condensing the vaporizedaniline hydrochloride in the presence of excess gaseous hydrogenchloride, and returning the latter to the process. 1 1 Signed by us this11th day of September,

MARK E. PUTNAM. LINDLEY E. MILLS.

from the reaction zone,

